-- libunbound based net.adns replacement for Prosody IM

-- Copyright (C) 2012-2015 Kim Alvefur

-- Copyright (C) 2012 Waqas Hussain

--

-- This file is MIT licensed.

local setmetatable = setmetatable;

local table = table;

local t_concat = table.concat;

local t_insert = table.insert;

local s_byte = string.byte;

local s_char = string.char;

local s_format = string.format;

local s_gsub = string.gsub;

local s_sub = string.sub;

local s_match = string.match;

local s_gmatch = string.gmatch;

local have_net, net_util = pcall(require, "util.net");

if have_net and not net_util.ntop then -- Added in Prosody 0.11

	have_net = false;

end

local chartohex = {};

for c = 0, 255 do

	chartohex[s_char(c)] = s_format("%02X", c);

end

local function tohex(s)

	return (s_gsub(s, ".", chartohex));

end

-- Converted from

-- http://www.iana.org/assignments/dns-parameters

local classes = {

	IN = 1; "IN";

	nil;

	CH = 3; "CH";

	HS = 4; "HS";

};

local types = {

"A";"NS";"MD";"MF";"CNAME";"SOA";"MB";"MG";"MR";"NULL";"WKS";"PTR";"HINFO";

"MINFO";"MX";"TXT";"RP";"AFSDB";"X25";"ISDN";"RT";"NSAP";"NSAP-PTR";"SIG";

"KEY";"PX";"GPOS";"AAAA";"LOC";"NXT";"EID";"NIMLOC";"SRV";"ATMA";"NAPTR";

"KX";"CERT";"A6";"DNAME";"SINK";"OPT";"APL";"DS";"SSHFP";"IPSECKEY";"RRSIG";

local errors = {

	NoError = "No Error"; [0] = "NoError";

	FormErr = "Format Error"; "FormErr";

	ServFail = "Server Failure"; "ServFail";

	NXDomain = "Non-Existent Domain"; "NXDomain";

	NotImp = "Not Implemented"; "NotImp";

	Refused = "Query Refused"; "Refused";

	YXDomain = "Name Exists when it should not"; "YXDomain";

	YXRRSet = "RR Set Exists when it should not"; "YXRRSet";

	NXRRSet = "RR Set that should exist does not"; "NXRRSet";

	NotAuth = "Server Not Authoritative for zone"; "NotAuth";

	NotZone = "Name not contained in zone"; "NotZone";

};

-- Simplified versions of Waqas DNS parsers

-- Only the per RR parsers are needed and only feed a single RR

local parsers = {};

-- No support for pointers, but libunbound appears to take care of that.

local function readDnsName(packet, pos)

	if s_byte(packet, pos) == 0 then return "."; end

	local pack_len, r, len = #packet, {};

	pos = pos or 1;

	repeat

		len = s_byte(packet, pos) or 0;

		t_insert(r, s_sub(packet, pos + 1, pos + len));

		pos = pos + len + 1;

	until len == 0 or pos >= pack_len;

	return t_concat(r, "."), pos;

end

-- These are just simple names.

parsers.CNAME = readDnsName;

parsers.NS = readDnsName

parsers.PTR = readDnsName;

local soa_mt = {

	__tostring = function(rr)

		return s_format("%s %s %d %d %d %d %d", rr.mname, rr.rname, rr.serial, rr.refresh, rr.retry, rr.expire, rr.minimum);

	end;

};

function parsers.SOA(packet)

	local mname, rname, offset;

	mname, offset = readDnsName(packet, 1);

	rname, offset = readDnsName(packet, offset);

	-- Extract all the bytes of these fields in one call

	local

		s1, s2, s3, s4, -- serial

		r1, r2, r3, r4, -- refresh

		t1, t2, t3, t4, -- retry

		e1, e2, e3, e4, -- expire

		m1, m2, m3, m4  -- minimum

			= s_byte(packet, offset, offset + 19);

	return setmetatable({

		mname = mname;

		rname = rname;

		serial  = s1*0x1000000 + s2*0x10000 + s3*0x100 + s4;

		refresh = r1*0x1000000 + r2*0x10000 + r3*0x100 + r4;

		retry   = t1*0x1000000 + t2*0x10000 + t3*0x100 + t4;

		expire  = e1*0x1000000 + e2*0x10000 + e3*0x100 + e4;

		minimum = m1*0x1000000 + m2*0x10000 + m3*0x100 + m4;

	}, soa_mt);

end

function parsers.A(packet)

	return s_format("%d.%d.%d.%d", s_byte(packet, 1, 4));

end

local aaaa = { nil, nil, nil, nil, nil, nil, nil, nil, };

function parsers.AAAA(packet)

	local hi, lo, ip, len, token;

	for i = 1, 8 do

		hi, lo = s_byte(packet, i * 2 - 1, i * 2);

		aaaa[i] = s_format("%x", hi * 256 + lo); -- skips leading zeros

	end

	ip = t_concat(aaaa, ":", 1, 8);

	len = (s_match(ip, "^0:[0:]+()") or 1) - 1;

	for s in s_gmatch(ip, ":0:[0:]+") do

		if len < #s then len, token = #s, s; end -- find longest sequence of zeros

	end

	return (s_gsub(ip, token or "^0:[0:]+", "::", 1));

end

if have_net then

	parsers.A = net_util.ntop;

	parsers.AAAA = net_util.ntop;

end

local mx_mt = {

	__tostring = function(rr)

		return s_format("%d %s", rr.pref, rr.mx)

	end

};

function parsers.MX(packet)

	local name = readDnsName(packet, 3);

	local b1,b2 = s_byte(packet, 1, 2);

	return setmetatable({

		pref = b1*256+b2;

		mx = name;

	}, mx_mt);

end

local srv_mt = {

	__tostring = function(rr)

		return s_format("%d %d %d %s", rr.priority, rr.weight, rr.port, rr.target);

	end

};

function parsers.SRV(packet)

	local name = readDnsName(packet, 7);

	local b1, b2, b3, b4, b5, b6 = s_byte(packet, 1, 6);

	return setmetatable({

		priority = b1*256+b2;

		weight   = b3*256+b4;

		port     = b5*256+b6;

		target   = name;

	}, srv_mt);

end

local txt_mt = { __tostring = t_concat };

function parsers.TXT(packet)

	local pack_len = #packet;

	local r, pos, len = {}, 1;

	repeat

		len = s_byte(packet, pos) or 0;

		t_insert(r, s_sub(packet, pos + 1, pos + len));

		pos = pos + len + 1;

	until pos >= pack_len;

	return setmetatable(r, txt_mt);

end

parsers.SPF = parsers.TXT;

-- Acronyms from RFC 7218

local tlsa_usages = {

	[0] = "PKIX-CA";

	[1] = "PKIX-EE";

	[2] = "DANE-TA";

	[3] = "DANE-EE";

	[255] = "PrivCert";

};

local tlsa_selectors = {

	[0] = "Cert",

	[1] = "SPKI",

	[255] = "PrivSel",

};

local tlsa_match_types = {

	[0] = "Full",

	[1] = "SHA2-256",

	[2] = "SHA2-512",

	[255] = "PrivMatch",

};

local tlsa_mt = {

	__tostring = function(rr)

		return s_format("%s %s %s %s",

			tlsa_usages[rr.use] or rr.use,

			tlsa_selectors[rr.select] or rr.select,

			tlsa_match_types[rr.match] or rr.match,

			tohex(rr.data));

	end;

	__index = {

		getUsage = function(rr) return tlsa_usages[rr.use] end;

		getSelector = function(rr) return tlsa_selectors[rr.select] end;

		getMatchType = function(rr) return tlsa_match_types[rr.match] end;

	}

};

function parsers.TLSA(packet)

	local use, select, match = s_byte(packet, 1,3);

	return setmetatable({

		use = use;

		select = select;

		match = match;

		data = s_sub(packet, 4);

	}, tlsa_mt);

end

local params = {

	TLSA = {

		use = tlsa_usages;

		select = tlsa_selectors;

		match = tlsa_match_types;

	};

};

local fallback_mt = {

	__tostring = function(rr)

		return s_format([[\# %d %s]], #rr.raw, tohex(rr.raw));

	end;

};

local function fallback_parser(packet)

	return setmetatable({ raw = packet },fallback_mt);

end

setmetatable(parsers, { __index = function() return fallback_parser end });

return {

	parsers = parsers;

	classes = classes;

	types = types;

	errors = errors;

	params = params;

};